First, make sure you have the sensors connected correctly.
The GREEN tip one goes into the MWTV receiver (Rx)
The BLACK tip one goes into the MWTV transmitter (Tx)
The sensor in the Rx simply goes on the shelf in the open so that when you point the cable box's remote to control the beam goes into the sensor.
The sensor plugged into the Tx must be on the shelf an inch to a half inch from the cable box front and must be lined up with the cable box IR eye on the box.
You may need two people. One with the cable boxes remote control where the MWTV Rx unit is located, the other person in the room with the cable box and the MWTV Tx
The person at the Rx pushes the Guide button or channel change button. If nothing happens, the person where the MWTV Tx is should begin moving the sensor slowly from the right-hand corner of the cable box to the left in small movements.
Once the Guide or channel changes, you would tape the MWTV Tx IR sensor to the shelf in front of the cable box where the change happened and mark the cable box with a drop of fingernail polish or grease pencil so that if the cable box is moved, you can easily line the sensor up again.